The mean surface temperature on Earth and other planets with atmospheres is determined by the radiative balance between the non-reflected incoming solar radiation and the outgoing long-wave black-body radiation from the atmosphere. The surface temperature is higher than the black-body temperature due to the greenhouse warming. Balancing the ice-albedo cooling and the greenhouse warming gives rise to two stable climate states. A cold climate state with a completelyice-covered planet, called Snowball Earth, and a warm state similar to our present climate where greenhouse warming prevents the total glacition. The warm state has dominated Earth in most of its geological history despite a 30 % fainter young Sun. The warming could have been controlled by a greenhouse thermostat operating by temperature control of the weathering process depleting the atmosphere from $CO_2$. This temperature control has permitted life to evolve as early as the end of the heavy bombartment 4 billion years ago.

Anyway, when I had discovered this, some suggestions came that I may well had discovered the flawed roots of that global warming discovery sequence. So I decided to start the mega project. I'm in the process of reviewing all abstracts under sciencemag.org sciencedirect.com and AGU.org that contain the string "Younger Dryas" for datable warm-cold indications, glacier advances and retreats and of course arid-humid changes. 200 abstracts down, some 300 to go.

Well with CO2 up 20-33 times the current values there would be some compensation for the fainter sun. But the greenhouse ice house idea s highly disputable. It's just what you want to see. Tectonics push the continents all over the planet in rom 200 million years AFAIK. Everytime when a continent passes a pole, it produces an ice sheet. One of the mass extinctions in the past may be attributed to the supercontinent Pangea, passing the south pole at the end of the Permian and created massive ice sheets and the remains of those can be found back at the equator. But that doesn't mean that there was a snow ball world. But that had nothing to with those flip flop ideas..